Allow NULL arg to OPENSSL_sk_{dup,deep_copy} returning empty stack

This simplifies many usages

Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14040)

2 files changed, 13 insertions, 12 deletions

diff --git a/doc/man3/DEFINE_STACK_OF.pod b/doc/man3/DEFINE_STACK_OF.pod
index 9088dc040b..b5908fead5 100644
--- a/doc/man3/DEFINE_STACK_OF.pod
+++ b/doc/man3/DEFINE_STACK_OF.pod
@@ -182,12 +182,14 @@ B<sk_I<TYPE>_sort>() sorts I<sk> using the supplied comparison function.
 
 B<sk_I<TYPE>_is_sorted>() returns B<1> if I<sk> is sorted and B<0> otherwise.
 
-B<sk_I<TYPE>_dup>() returns a copy of I<sk>. Note the pointers in the copy
-are identical to the original.
+B<sk_I<TYPE>_dup>() returns a shallow copy of I<sk>
+or an empty stack if the passed stack is NULL.
+Note the pointers in the copy are identical to the original.
 
 B<sk_I<TYPE>_deep_copy>() returns a new stack where each element has been
-copied. Copying is performed by the supplied copyfunc() and freeing by
-freefunc(). The function freefunc() is only called if an error occurs.
+copied or an empty stack if the passed stack is NULL.
+Copying is performed by the supplied copyfunc() and freeing by freefunc().
+The function freefunc() is only called if an error occurs.
 
 =head1 NOTES
 
@@ -258,7 +260,7 @@ B<sk_I<TYPE>_is_sorted>() returns B<1> if the stack is sorted and B<0> if it is
 not.
 
 B<sk_I<TYPE>_dup>() and B<sk_I<TYPE>_deep_copy>() return a pointer to the copy
-of the stack.
+of the stack or NULL on error.
 
 =head1 HISTORY
 
diff --git a/doc/man3/X509_new.pod b/doc/man3/X509_new.pod
index b40715bddf..ab310bff57 100644
--- a/doc/man3/X509_new.pod
+++ b/doc/man3/X509_new.pod
@@ -2,9 +2,9 @@
 
 =head1 NAME
 
-X509_chain_up_ref,
 X509_new, X509_new_ex,
-X509_free, X509_up_ref - X509 certificate ASN1 allocation functions
+X509_free, X509_up_ref,
+X509_chain_up_ref - X509 certificate ASN1 allocation functions
 
 =head1 SYNOPSIS
 
@@ -37,7 +37,7 @@ frees it up if the reference count is zero. If B<a> is NULL nothing is done.
 X509_up_ref() increments the reference count of B<a>.
 
 X509_chain_up_ref() increases the reference count of all certificates in
-chain B<x> and returns a copy of the stack.
+chain B<x> and returns a copy of the stack, or an empty stack if B<a> is NULL.
 
 =head1 NOTES
 
@@ -46,20 +46,19 @@ used by several different operations each of which will free it up after
 use: this avoids the need to duplicate the entire certificate structure.
 
 The function X509_chain_up_ref() doesn't just up the reference count of
-each certificate it also returns a copy of the stack, using sk_X509_dup(),
+each certificate. It also returns a copy of the stack, using sk_X509_dup(),
 but it serves a similar purpose: the returned chain persists after the
 original has been freed.
 
 =head1 RETURN VALUES
 
-If the allocation fails, X509_new() returns B<NULL> and sets an error
+If the allocation fails, X509_new() returns NULL and sets an error
 code that can be obtained by L<ERR_get_error(3)>.
 Otherwise it returns a pointer to the newly allocated structure.
 
 X509_up_ref() returns 1 for success and 0 for failure.
 
-X509_chain_up_ref() returns a copy of the stack or B<NULL> if an error
-occurred.
+X509_chain_up_ref() returns a copy of the stack or NULL if an error occurred.
 
 =head1 SEE ALSO